‘He knows what he has to do: get outside, and disappear.’
Photograph: Petri Oeschger/Getty Images

In the 23 years we lived at our old house the tortoise was an undemanding pet: in the summer he stalked the garden freely; in the winter he held the kitchen door open. He’s not affectionate, but he’s quiet. He’s also about 50 years old – my wife has had him since she was eight – and will probably outlive us. When you know you’re going to have to bequeath a pet to someone eventually, the fact that it requires very little maintenance is a plus.

Things are different in the new house – the garden is full of seedlings and unestablished annuals, with no raised borders. Left to his own devices, the tortoise will mow through a whole bed in an afternoon. What he can’t eat, he squashes. My wife bought a rabbit run to pen him in, but every moment he’s in it is spent trying to figure a way out. I find this very hard to watch.

“He hates it,” I say.

“He’s got to learn,” my wife says.

“He’s going to win this,” I say. “I know it, and you know it.”

Here is the new routine: in the morning my wife puts the tortoise in the rabbit run on the lawn, with a few radish tops for company. I spend an hour sitting in my office shed watching the tortoise circle the perimeter of his cage, probing for weak points. When I can’t stand it any longer, I lift him out and place him where I can keep an eye on him. The next time I look, he is gone.

At about midday my wife comes out and starts screaming about some decimated sweet peas.

“Why did you let him out?” she says.

“I didn’t,” I say. “He must have climbed over the bars.”

“Don’t be stupid,” she says.

“I’m not telling you how he does it,” I say. “Because I’m on his side.” She puts the tortoise in the kitchen, where it crawls under the dog’s bed to sulk. The next day, the routine is repeated.

I try providing the tortoise with such a bounty of salad that he has no room left for annuals, but he likes variety: two grapes, a lettuce leaf, a bit of bindweed and an entire bush my wife planted the day before. The next day I wake the youngest one at midday.

“I need you to babysit the tortoise while I work,” I say. The duvet flaps down to reveal one cold blue eye.

“Do I have to read to it?” he says.

“Just follow him around and keep him out of trouble,” I say. “After two hours I’ll take over.”

“Yeah, I’m not doing that,” he says.

“One day you’ll look back and realise it was the best job you ever had,” I say. The duvet flaps up.

On Tuesday I make a big speech about the monstrous injustice of the cage, and disassemble it. On Wednesday morning my wife refuses to put the tortoise outside, but once she leaves the house he pushes open the garden door and thunks down three steps. I turn to find him outside my office staring up at me, with an expression that says: if anyone asks, you haven’t seen me.

Unfortunately when my wife comes home the tortoise is still there, sunning himself on the bricks.

“Look,” I say. “He’s learned.”

“He hasn’t,” she says, picking him up. “And neither have you.”

For two days the weather is overcast and cold, and the tortoise doesn’t stir from under the dog bed. On the next sunny morning he knows what he has to do: get outside, and disappear.

At about 11 I hear the thunk of his shell as he negotiates the kitchen step, but I don’t look up. At 12 he passes my office door with some leaves hanging off his chin, but I say nothing. At sunset my wife goes looking for the tortoise, but she can’t find him.

“You’ve done this,” she says.

“I’ve done nothing,” I say.

I see him most mornings these days, but by afternoon he’s under cover and by evening he’s back in his hiding place. To be honest, I know exactly where he goes, but my lips are sealed.